The comparison of the in-house and real-time PCR methods used in the diagnosis of tuberculosis

Aim: The World Health Organization (WHO) tests new PCR methods developed for TB diagnosis, approves some of them those with high diagnostic performance and recommends their use in routine diagnosis. However, the high cost of such approved methods reduces their use in areas with limited resources. This study aimed to compare the effectiveness of an in-house PCR and a commercial real-time PCR kit in detecting Mycobacterium tuberculosis bacillus complex in clinical samples with of the TB-PCR kit recommended by WHO. Materials and Methods: Among the samples sent to İnönü University Turgut Özal Medical Center TB Diagnostic Laboratory between 01 January 2018 and 31 December 2022; a total of 242 clinical samples, whose classical TB-diagnostic tests and TB-PCR tests were performed with Xpert MTB/RIF Ultra (Cepheid, USA) kits recommended by WHO and whose results were reported, were included in the study. T11-T12 primers were used in the in-house PCR method, and Artus® M.tuberculosis RG-PCR kit (Qiagen, Germany) was used as commercial real-time PCR. The diagnostic performance values of these two PCR methods were compared with the WHO-approved PCR method. Results: Of the 242 samples studied, 167 were TB-positive and 75 were TB-negative. 165 of the samples were detected as positive by WHO-approved PCR and the remaining 77 were negative. The concordance of T11-T12 in-house PCR with the WHO-approved kit in positive and negative samples was determined as 78.72% and 96.10%, respectively. The agreement between the Artus real-time PCR and the WHO-approved kit in positive and negative samples was found to be 87.23% and 98.70%, orderly. In the study, the sensitivity of in-house PCR was 71.25% and the specificity was 97.33%; The sensitivity of Artus real-time PCR was found to be 74.25% and the specificity was 99.40%. Discussion: The results obtained showed that both alternative PCR methods studied showed 93% and above agreement with the WHO-approved PCR kit in detecting negative samples; however, it has shown that agreement in detecting positives can range from 57% to 87%, depending on the bacillary load in the sample. Keywords: Mycobacterium tuberculosis bacilli complex bacilli (MTBC), Artus M. tuberculosis RG, Xpert MTB/RIF Ultra, hsp65, T11-T12 DNA primers, molecular diagnosis.